Next-generation self-adhesive dressings: Highly stretchable, antibacterial, and UV-shielding properties enabled by tannic acid-coated cellulose nanocrystals.

Hydrogels with excellent high-water uptake and flexibility have great potential for wound dressing. However, pure hydrogels without fiber skeleton faced poor water retention, weak fatigue resistance, and mechanical strength to hinder the development of the dressing as next-generation functional dressings. We prepared an ultrafast gelation (6 s) Fe3+/TA-CNC hydrogel (CTFG hydrogel) based on a self-catalytic system and bilayer self-assembled composites. The CTFG hydrogel has excellent flexibility (800% of strain), fatigue resistance (support 60% compression cycles), antibacterial, and self-adhesive properties (no residue or allergy after peeling off the skin). CTFG@S bilayer composites were formed after electrospun silk fibroin (SF) membranes were prepared and adhesive with CTFG hydrogels. The CTFG@S bilayer composites had significant UV-shielding (99.95%), tensile strain (210.9 KPa), and sensitive humidity-sensing properties. Moreover, the integrated structure improved the mechanical properties of electrospun SF membranes. This study would provide a promising strategy for rapidly preparing multifunctional hydrogels for wound dressing.

Deep insights into biodegradability mechanism and growth cycle adaptability of polylactic acid/hyperbranched cellulose nanocrystal composite mulch.

The widespread use of petroleum-based plastic mulch in agriculture has accelerated white and microplastic pollution while posing a severe agroecological challenge due to its difficulty in decomposing in the natural environment. However, endowing mulch film with degradability and growth cycle adaptation remains elusive due to the inherent non-degradability of petroleum-based plastics severely hindering its applications. This work reports polylactic acids hyperbranched composite mulch (PCP) and measured biodegradation behavior under burial soil, seawater, and ultraviolet (UV) aging to understand the biodegradation kinetics and to increase their sustainability in the agriculture field. Due to high interfacial interactions between polymer and nanofiler, the resultant PCP mulch significantly enhances crystallization ability, hydrophilicity, and mechanical properties. PCP mulch can be scalable-manufactured to exhibit modulated degradation performance under varying degradation conditions and periods while concurrently enhancing crop growth (wheat). Thus, such mulch with excellent performance can reduce labor costs and the environmental impact of waste mulch disposal to replace traditional mulch for sustainable agricultural production.

Multiple noncovalent interactions tailored crystallization and performance reinforcement mechanisms of Biopolyester Composites with functional Cellulose Nanocrystals.

The slow crystallization and weak mechanical features of poly (butylene adipate-co-terephthalate) (PBAT) have become a severe industrial problem in food packaging. Inspired by principle of bionic structure, functional cellulose nanocrystals (CNC) modified with hexamethylene diisocyanate (HMDI) and toluene diisocyanate (TDI) can enhance the crystallization ability and mechanical properties of PBAT nanocomposites. Significantly, CNC-T (CNC modified by TDI) showed a stronger reinforced effect on PBAT properties than unmodified CNCs and CNC-H (CNC modified by HMDI) nanofillers due to hydrogen bonds, π-π interaction between PBAT matrix and CNC-T nanofillers with benzene ring structure. Thus, compared with pure PBAT, PBAT/5CNC-T composites displayed an enhancement of 34.5 % on the tensile strength and exhibited the most robust nucleation ability on PBAT crystallization than CNC and CNC-H. Meanwhile, the possible nucleation, crystallization, and performance reinforcement mechanisms of PBAT nanocomposites have been presented, which is very beneficial for designing robust PBAT nanocomposites with functional cellulose nanocrystals for potential green packaging.

Multi-functional nanocellulose based nanocomposites for biodegradable food packaging: Hybridization, fabrication, key properties and application.

Nowadays, non-degradable plastic packaging materials have caused serious environmental pollution, posing a threat to human health and development. Renewable eco-friendly nanocellulose hybrid (NCs-hybrid) composites as an ideal alternative to petroleum-based plastic food packaging have been extensively reported in recent years. NCs-hybrids include metal, metal oxides, organic frameworks (MOFs), plants, and active compounds. However, no review systematically summarizes the preparation, processing, and multi-functional applications of NCs-hybrid composites. In this review, the design and hybridization of various NCs-hybrids, the processing of multi-scale nanocomposites, and their key properties in food packaging applications were systematically explored for the first time. Moreover, the synergistic effects of various NCs-hybrids on several properties of composites, including mechanical, thermal, UV shielding, waterproofing, barrier, antimicrobial, antioxidant, biodegradation and sensing were reviewed in detailed. Then, the problems and advances in research on renewable NCs-hybrid composites are suggested for biodegradable food packaging applications. Finally, a future packaging material is proposed by using NCs-hybrids as nanofillers and endowing them with various properties, which are denoted as "PACKAGE" and characterized by "Property, Application, Cellulose, Keen, Antipollution, Green, Easy."

All-naturally structured tough, ultrathin, and washable dual-use composite for fruits preservation with high biosafety evaluation.

This work develops a sustainable and global strategy to enhance fruit preservation efficacy. The dual-use composite coating or film comprises silk fibroin/cellulose nanocrystals (SF/CNC) with superior ductility through a synergistic plasticizing effect of glycerol and natural aloe-emodin powder (AE) as antimicrobial agents. To confirm our strategy, two common fruit preservation materials (edible surface coating-SCA-CS; packaging film-SCA-PF) and five different fruits (strawberries, bananas, apples, blueberries, and guavas) have been used. Moreover, SCA-CS coating with antibacterial and antioxidant activities formed an ultrathin layer on the fruit's surfaces with a thickness of 7.7 µm and could be easily washable. Therefore, bananas and strawberries' shelf-life with SCA-CS coating can be extended for 9 days and 6 days, respectively. The discharge water of SCA-CS has excellent biosafety in an indoor environment with no threat to plant health (microgreens bean sprouts germination as a case study). The plant exhibited positive results within 15 days, and leaves maintained their green color with a germination rate of 97.6 %. The toughness of SCA-PF film increased by 14,685.7 % with a water vapor transmission rate (WPTR) of 17 g mm m-2 day-1, which confirms that the concept of SCA-PF film and SCA-CS coating are feasible to be used for fruit preservation/packaging.

One-pot strategy to fabricate conductive cellulose nanocrystal-polyethylenedioxythiophene nanocomposite: Synthesis mechanism, modulated morphologies and sensor assembly.

Simple preparation, good conductivity, and excellent hydrophilicity are in urgent demand due to fast growth of wearable intelligent devices. Cellulose nanocrystal-polyethylenedioxythiophene (CNC-PEDOT) nanocomposites with modulated morphology were prepared through Iron (III) p-toluenesulfonate hydrolysis of commercialized microcrystalline cellulose (MCC) and in situ polymerization of 3,4-ethylenedioxythiophene monomers (EDOT) through one-pot green synthesis, where preparation and modification of CNC were obtained for uses as templates to anchor PEDOT nanoparticles. The resultant CNC-PEDOT nanocomposite gave well-dispersed PEDOT nanoparticles with sheet-like structure on the CNC surface, possessing higher conductivity and improved hydrophilicity or dispersibility. Subsequently, a wearable non-woven fabrics (NWF) sensor was successfully assembled by dipping the conductive CNC-PEDOT, and showed excellent sensing response for multiple signals (subtle deformation from various human activities and temperature). This study provides a feasible and large-scale production of CNC-PEDOT nanocomposites and their applications in wearable flexible sensors and electronic devices.

Thermo-sensitive composite microspheres incorporating cellulose nanocrystals for regulated drug release kinetics.

Thermo-sensitive composite microspheres (TPCP) were developed to achieve the on-demand release of drugs. The TPCP microspheres were synthesized using Oil-in-Water (O/W) emulsion evaporation technique and then impregnated with thermo-sensitive polyethylene glycol (PEG). The addition of cellulose nanocrystals (CNCs) significantly enhance thermal stability, crystallization ability, and surface hydrophilicity of TPCP microspheres due to heterogeneous nucleation effect and hydrogen bonding interaction, resulting in stable microsphere structure. The thermal degradation temperature (Tmax) increased by 13.8 °C, and the crystallinity improved by 20.9 % for 10 % TPCP. The thermo-sensitive composite microspheres showed the regulated cumulative release according to in vitro human physiological temperature changes. Besides, four release kinetics and possible release mechanism of TPCP microspheres were provided. Such thermo-responsive composite microspheres with control microsphere sizes and high encapsulation rate may have the potential to the development of on-demand and advanced controlled-release delivery systems.

A comprehensive investigation on cellulose nanocrystals with different crystal structures from cotton via an efficient route.

The crystal structures of cellulose nanomaterials play an important role in their morphologies and applications, however, there was still lacking systematic research on preparing various crystalline allomorphs of cellulose nanocrystals with high thermal stability. Herein, the efficient synthesis route was presented to design various crystalline allomorphs of cellulose from cotton. And then, cellulose nanocrystals with different crystal structures (CNC-I, CNC-II, CNC-IIIII, CNC-IVII) were prepared by hydrogen peroxide hydrolysis of resultant cellulose. Overall, needle-like CNC-I (length of 180 ± 25 nm, diameter of 12 ± 2 nm), near-spherical CNC-II (diameter of 101 ± 12 nm), and spherical CNC-IIIII (diameter of 22 ± 3 nm) and CNC-IVII (diameter of 21 ± 2 nm) all exhibited remarkable dispersibility and thermal stability (Tmax > 357 °C). This work provides a simple and low-cost synthesis route for various crystalline allomorphs of CNCs with high thermal stability from the same raw materials (cotton).

Continuous Meter-Scale Wet-Spinning of Cornlike Composite Fibers for Eco-Friendly Multifunctional Electronics.

"Green" solvent-dissolved cellulose enables functional reuse of waste cotton fabrics. This work will not only achieve high-value utilization of biomass but also overcome microplastic pollution. There is a significant challenge in the continuous meter-scale synthesis of sensing fibers for commercial applications with high productivity. Herein, waste cellulose fabrics was recycled by the NaOH/urea system to produce regenerated cellulose (RC) and then cornlike polyaniline (PANI) was anchored on the RC fibers by in situ polymerization of aniline through continuous meter-scale wet-spinning. In our findings, the morphologies and possible growth of PANI layers on the RC surface can be tailored by various ammonium persulfate (APS) contents in a coagulation bath. Especially, composite fibers (PC0.5) exhibited superior electrical conductivity and highly sensitive responsiveness to organic vapors and human motions including exhalation/inhalation, finger, and wrist joints. Further, the possible sensing mechanism of cornlike PC0.5 has been proposed, and its GF value is 23.8. This study realized the conversion from cheap waste fibers to high-value conductive fibers with excellent performances for multifunctional wearable sensors and energy devices via a simple and "green" method.

Multifunctional Biosensors Made with Self-Healable Silk Fibroin Imitating Skin.

We report on robust silk fibroin (SF) gels fabricated by incorporating cellulose nanocrystals (SF/CNC) as a "tough" unit and photopolymerization of acrylamide as an "elastic" segment. The addition of CNC affects the refolding process of SF molecules controlled by nucleation via templating, resulting in a stable mesoscopic structure. The gel shows robust mechanical stability (88.8% of initial stress after 1000 compression cycles) and excellent adhesion to various materials. The connected gel can recover its ionic conductivity within 20 s and be stretched to a maximum strain of 498% after healing for 10 h with an efficiency of 95.2%. This multifunctional gel sensor can sensitively detect different toxic gases and small-scale and large-scale human motions in real-time. Its sensitivity is calculated as GF = 3.84 at 0-200% strain. Especially, the gel with 5 wt % thermochromic pigments as a visual temperature indicator can quickly reflect abnormal human body temperature according to the color change. Therefore, the strategy shows potential applications in flexible electrodes, biomimetic sensors, and visual biosensors.

Versatile nanocellulose-based nanohybrids: A promising-new class for active packaging applications.

The food packaging industry is rapidly growing as a consequence of the development of nanotechnology and changing consumers' preferences for food quality and safety. In today's globalization of markets, active packaging has achieved many advantages with the capability to absorb or release substances for prolonging the food shelf life over the traditional one. Therefore, it is critical to developing multifunctional active packaging materials from biodegradable polymers with active agents to decrease environmental challenges. This review article addresses the recent advances in nanocelluloses (NCs)- baseds nanohybrids with new function features in packaging, focusing on the various synthesis methods of NCs-based nanohybrids, and their reinforcing effects as active agents on food packaging properties. The applications of NCs-based nanohybrids as antioxidants, antimicrobial agents, and UV blocker absorbers for prolonging food shelf-life are also reviewed. Overall, these advantages make the CNs-based nanohybrids with versatile properties promising in food and packaging industries, which will impact more readership with concern for future research.

Magnetic cellulose nanocrystals hybrids reinforced phase change fiber composites with highly thermal energy storage efficiencies.

The intrinsic intermittence of solar energy raises the necessity for thermal energy storage (TES) systems to balance the contradiction between energy supply and demand energy. This work experimentally provides solid-liquid phase change materials (PCMs) with sufficient storage capacity and discharging rate to offer heating for agriculture products by enhancing heat transfer in phase change fiber composites (PCF). To achieve this, we prepared dipole responsive magnetic/solar-driven PCF composites reinforced with magnetic cellulose nanocrystals hybrids (MCNC). The obtained PCF/MCNC-5% showed excellent magnetic property with a saturation magnetization (MS) value of 1.3 emu/g and effective latent heat phase change enthalpies of 69.2 ± 3.5 J/g - 83.1 ± 4.2 J/g. More importantly, PCF/MCNC-5% showed robust high magnetic to thermal energy storage efficiency of 32.5 % and solar light accelerated energy storage efficiency of 58.5 %. These advantages make the PCF composites promising and more desirable for drying and preservation of the fruits and other agriculture products.

Double stimuli-responsive cellulose nanocrystals reinforced electrospun PHBV composites membrane for intelligent drug release.

Double stimuli-responsive functionalized cellulose nanocrystal-poly[2-(dimethylamino)ethyl methacrylate] (CNC-g-PDMAEMA) reinforced poly(3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) electrospun composite membranes were explored as drug delivery vehicles using tetracycline hydrochloride (TH) as a model drug. It was found that rigid CNC-g-PDMAEMA nanoparticles enhanced thermal, crystallization and hydrophilic properties of PHBV. Moreover, great improvements in fiber diameter uniformity, crystallization ability and maximum decomposition temperature (Tmax) could be achieved at 6 wt% CNC-g-PDMAEMA. Furthermore, by introducing stimuli-responsive CNC-g-PDMAEMA nanofillers, intelligent and long-term sustained release behavior of composite membranes could be achieved. The releasing mechanism of composite membranes based on zero order, first order, Higuchi and Korsmeyere-Peppas mathematical models was clearly demonstrated, giving effective technical guidance for practical drug delivery systems.

Bifunctional Reinforcement of Green Biopolymer Packaging Nanocomposites with Natural Cellulose Nanocrystal-Rosin Hybrids.

Rosin and cellulose nanocrystals (CNCs) are easily extracted from agricultural pines/conifers and natural cellulose, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is extracted from agricultural corn stalks, etc. In this study, PHBV and CNC-grafted rosin (CNC-R) hybrids were successfully fabricated by an efficient solution casting. The nanocomposites with a homogenous microstructure were transparent and had strong barrier resistances to water vapor and two food simulants. The synchronous enchantments in mechanical strength/toughness and thermal stability of nanocomposite films were achieved by addition of CNC-R. The T0 increased by 31.2 °C for the film with 10 wt % CNC-R; meanwhile, the tensile strength and elongation to break were improved by 107.9 and 43.9% for the sample using 5 wt % CNC-R, respectively. Also, compared to neat PHBV, the nanocomposites with 5 wt % CNC-R exhibited excellent barrier properties, antibacterial activity (100.0% antibacterial ratio), and lower migration levels for both food simulants. The appearance of coated grapes with 10 wt % CNC-R nanocomposites at the 11th day was the best compared to those of PHBV and its nanocomposites with a low CNC-R content (1-3 wt %). Thus, our nanocomposites with CNC-R showed a significant application in packaged grape by extended shelf life and had potential applications in bioactive food packaging materials.

Enhancing long-term biodegradability and UV-shielding performances of transparent polylactic acid nanocomposite films by adding cellulose nanocrystal-zinc oxide hybrids.

We investigated UV-shielding performances and biodegradation abilities under controlled hydrolytic, soil burial, and thermal conditions of transparent polylactic acids (PLA) nanocomposite films embedded with cellulose nanocrystal-zinc oxide (CNC-ZnO) hybrids. By adding high content of 15wt %CNC-ZnO hybrids into the PLA matrix, the highest UV radiation was blocked out by (85.31%) of UV-A and (95.90%) of UV-B. It is found that the weight loss of PLA nanocomposites after being hydrolytic degraded for 70 days increased from 9% for PLA to 25% with 15 wt% CNC-ZnO hybrids. Meanwhile, in soil burial test, pure PLA shows smallest degradation rate with only 8% weight loss after 110 days, while the PLA nanocomposite film with 15 wt% CNC-ZnO hybrids was degraded by about 28%. Besides, the resultant degradation byproducts from the thermally-decomposed catalysis have been identified by Fourier transform infrared spectroscopy (FT-IR). Moreover, the morphologies and appearances changes during the hydrolytic and soil degradation of PLA nanocomposite films were evaluated. This study is expected to provide meaningful insights into nanocomposite films embedded with CNC-ZnO hybrids as a result of contourable degradation and high ultraviolet protection factor value (UPF).

Natural Biodegradable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Nanocomposites with Multifunctional Cellulose Nanocrystals/Graphene Oxide Hybrids for High-Performance Food Packaging.

High-performance and useful graphene oxide (GO) and cellulose nanocrystals (CNCs) are easily extracted from natural graphite and cellulose raw materials, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is produced by bacterial fermentation from natural plant corn stalks, etc. In this study, novel ternary nanocomposites consisting of PHBV/cellulose nanocrystal-graphene oxide nanohybrids were prepared via a simple solution casting method. The synergistic effect of CNC with GO nanohybrids obtained by chemical grafting (CNC-GO, covalent bonds) and physical blending (CNC/GO, noncovalent bonds) on the physicochemical properties of PHBV nanocomposites was evaluated and the results compared with a single component nanofiller (CNC or GO) in binary nanocomposites. More interestingly, ternary nanocomposites displayed the highest thermal stability and mechanical properties. Compared to neat PHBV, the tensile strength and elongation to break increased by 170.2 and 52.1%, respectively, and maximum degradation temperature (Tmax) increment by 26.3 °C, were observed for the ternary nanocomposite with 1 wt % covalent bonded CNC-GO. Compared to neat PHBV, binary, and 1:0.5 wt % noncovalent CNC/GO based nanocomposites, the ternary nanocomposites with 1 wt % covalent bonded CNC-GO exhibited excellent barrier properties, good antibacterial activity (antibacterial ratio of 100.0%), reduced barrier properties, and lower migration level for both food simulants. Such a synergistic effect yielded high-performance ternary nanocomposites with great potential for bioactive food packaging materials.

Green one-step synthesis of ZnO/cellulose nanocrystal hybrids with modulated morphologies and superfast absorption of cationic dyes.

Zinc oxide/cellulose nanocrystal (ZnO/CNC) hybrids with modulated morphologies were prepared by using bamboo CNC as templates via green one-step technique. The effect of pH values on the morphology, microstructure, thermal stability, antibacterial efficiency and dye absorption kinetics of hybrids were investigated. A possible mechanism for various hybrid morphologies at different pH values was provided. All the samples exhibited high antibacterial ratios of 91.4%-99.8% against both Escherichia coli and Staphylococcus aureus. ZnO/CNC8.5 gave quick removal efficiency with high dye removal ratios in methylene blue (MB, 93.55%) and malachite green (MG, 99.02%), especially >91.47% and 97.85% within 5 min. The absorption capacity could reach up to 46.77 mg/g for MB and 49.51 mg/g for MG. Besides, absorption kinetics showed that the absorption behavior followed the pseudo-second-order kinetic model (R2 > 0.99996). Such ZnO/CNC hybrids show outstanding and low-cost adsorbent for efficient absorption of cationic dyes in wastewater treatment field.

Fabrication of metal-organic frameworks@cellulose aerogels composite materials for removal of heavy metal ions in water.

In the present work, we develop novel method of loading metal-organic frameworks (UiO-66 and UiO-66-NH2) on the flexible cellulose aerogels as metal-organic frameworks@cellulose aerogels composite materials by using in situ growth procedure at room temperature. The as prepared metal-organic frameworks@cellulose aerogels composite materials were well characterized via SEM, XRD, atomic absorption spectrometer, and TG analysis, besides the adsorption of Pb2+ and Cu2+ in metal-organic frameworks@cellulose aerogels composite materials was investigated. The amount of metal ions adsorbed by metal-organic frameworks@cellulose aerogels composite materials is equal to the sum of metal-organic frameworks and cellulose aerogels, indicating that the metal-organic frameworks are not blocked after cellulose aerogels growth and still have adsorption properties. It was found that metal-organic frameworks@cellulose aerogels composite materials can be recycled to adsorb Pb2+ and Cu2+ in water after simple cleaning. The equilibrium adsorption capacity of Pb2+ adsorbed by UiO-66-NH2@CA was 89.40 mg g-1, and can be easily reused for more than 5 cycles without significant decrease in performance. Moreover, the maximum decomposition temperature (Tmax) of UiO-66-NH2@CA was increased by 62.1℃. This result suggested that such metal-organic frameworks@cellulose aerogels composite materials could adsorb heavy metal ions in water could by avoiding secondary pollution and show great potential in water treatment.

Sheet-like Cellulose Nanocrystal-ZnO Nanohybrids as Multifunctional Reinforcing Agents in Biopolyester Composite Nanofibers with Ultrahigh UV-Shielding and Antibacterial Performances.

The uses of inorganic metal oxide and ZnO nanohybrids as UV absorbers have potential to increase the production of UV-protective textile, which will also overcome the drawbacks of organic molecules and prevent negative impacts on human health and environment. In this work, sheet-like cellulose nanocrystal-ZnO (CNC-ZnO) nanohybrid was successfully developed by one-step hydrothermal method. The obtained CNC-ZnO nanohybrids as UV absorber and antibacterial agents were introduced into biopolyester (poly(3-hydroxybutyrate-co-3-hydroxy valerate, PHBV) by using electrospinning process. The addition of sheet-like CNC-ZnO can greatly enhance PHBV thermal stability and crystallization ability. In addition, excellent antimicrobial ratios of Escherichia coli and Staphylococcus aureus and high absorbency of solution A (9.82 g/g) were obtained for the composite nanofibers with 5 wt % CNC-ZnO. Moreover, most of the UV irradiations were blocked out for both UVA (99.72%) and UVB (99. 95%) with high UPF value of 1674.9 in the resulting composite nanofibers with 9 wt % CNC-ZnO. This study provides a novel method to produce sheet-like CNC-ZnO with multifunctional properties and its nanocomposite for potential uses as wound dressings and other functional biomaterials.

In vitro degradation and possible hydrolytic mechanism of PHBV nanocomposites by incorporating cellulose nanocrystal-ZnO nanohybrids.

Fabrication and characterization of bbiodegradable nanocomposites based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix reinforced with cellulose nanocrystal (CNC)-ZnO nanohybrids via simple solution casting for possible use as antibacterial biomedical materials is reported. The obtained nanocomposites exhibited an excellent antibacterial ratio of 95.2-100% for both types of bacteria namely S. aureus and E. coli and showed 9-15% degradation after one week. The addition of CNC-ZnO showed a positive effect on hydrophilicity and barrier properties. More significantly, the nanocomposites with 10wt% CNC-ZnO showed enhancement in tensile strength (140.2%), Young's modulus (183.1%), and the maximum decomposition temperature (Tmax) value increased by 26.1°C. Moreover, this study has provided a possible mechanism for using such nanofillers on the hydrolytic degradation of PHBV, which was beneficial to obtain the high-performance nanocomposites with modulated degradation rate for antibacterial biomaterials.